A liar, especially a man. Used in Latino English and Spanglish, from Spanish.

"Get out papí I ain't gon make love to no mentiroso"
"Maricon te digo que no debes salir con él cuz he a mentiroso" (Bro I am telling you not to go out with him cuz he a -.)
"Mamí no te voy a engañar, crees que I'm a mentiroso or somethin?" (Girl, I'm not going to cheat on you, do you think I'm a liar or something?)